Metal-filaments.



- cation.- 1

CHARLES A. HANSEN, OF SCHENECTADY,.NEWJYORK,AS3IGN.QR TB ELEC-..

TRIGLQOMIEANY, .A. G9BRORA TIQN DF NEWIIORK...L

Maren-r :rIn-nMEN'rs.

No Drawing.

To all wlkome'tzmay. concern: H/

Be it known that L' OI-IARLES A: HANSEN,-1! a citizen of the 1' United States,- residing. .at Schenectady, county of Schenectady, .fitate; of New York, have inventedcertain new; and. useful Improvements=-in Metat .aFila- S mente,.of which theeifollowingiis a speoifie This invention-melates-Jto. the production of refractory imetal filaments. According-1 to my invention :the' refractory: metahzisi ob"! tained from a reducible 'rcompoundof the metal by heating that compound in a reducing chamber'under low" ressure and then, if desired, heating the re uction materialsto. a high temperature, andlotherwise. improving the product. 7

I have hereinafter described my process as applied to the manufacture of tungsten filaments, but I consider that my processinvolves certain novel steps which are apph-w.

cable to other metals than tungsten, and are particularly applicable to the treatment of compounds of the high fusing metals.-

In applying my invention to practice, I produce a squirtlngmixture containing a reducible compound of the refractory metal, such for instance as oxid, and I reduce this oxid by heat treatment in the presence of hydrogen or other volatile reducing agent under low pressure. I consider that the pressure of the reducin agent has an importantbearing on t e reduction, and furthermore, has a very important bearing on the proportion of carbon left in the product, whether that carbon rises as an impurity in the oxid or comes from the binding material used when the oxid is squirted. If,tunsten trioxid, W0 is'used I prefer to mix with it a decomposable carbonaceous binding -material, such for instance as glucose, which may be subsequently disintegrated or decomposed by heat. Glucose is, however only one of many binding materials which are suitable for this work, and I have obtained very satisfactory results with a binder containing glucose, starch, and glycerin. The glycerin prevents rapid dryin of the mixture,the starch gives it smoot ness, and the glucose gives it strength for squirting: These ingredients ma be used in the following proportions 0 -3918 parts by weight; g1ucose 1.2 parts; starch-1 part, and glycerin-3 parts. This mixture when .may' he readiiy woundwn a: formand otherratenteaoeam, 1913...

sqtlirtedegives a good: smooth-thread whichuwise manipulated-to produce' filamentsor I -r'tincandescing conductors 1 of the desired shape; Thernextstep-iin. my process consists in baking-theiraw;filaments in an i orjdinarymufile furnace-at about150 centigriadee forctendminutes;=this =is to dry the filaments andnstifi'eniithemml next carbonize .ithetfilaments. foreten minutesin a mufflevcarbonized.filanments. in a. graphite crucible and-firein a resistance furnace in an atmos- I next pump out all the hydrogen from thefurnace and increase the energy input to about 7 kilowatts and continue the heating operation for about one hour. I estimate that the temperature under these conditions is in the neighborhood of 2200 centigrade and I believe that no carbon remains in the filament after this last treatment, for I find that filaments which have been so treated may, be run for some time at a current consun'rption as low as .3 of a watt per candle. I think it very possible that by working under reduced pressure, the activity of the carbon as a reducing agent is much increased phereof hydrogen at a pressure of about 20 and the temperature of reduction is lowered.

lamp, though if desired they. maybe first mounted on the lamp stem and then given a preliminary heat treatment in an evacuated treating chamber or in an inert gas, by passlug current through'the filaments to shrink them and put them in better condition for continuous operation in the lamp.

Where'in the appended claims I refer spezifically to the production of filaments of tungsten, I wish it to be understood that the production offilaments, or other shaped aricles, of other refractory metals having similar properties is to be included thereby.

What I claim as new and desire to secure 3y Letters Patent of the United States, is,-

1. A squirtable mixture for the manufacbure of lamp filaments consistin of an oxid 3f tungsten, starch, glycerin an glucose.

2. The process which consists in heating lamp filament material containing an oxid )f tungsten and carbon in areducing atmosphere at low pressure to reduce the oxid and aliminate the carbon, and in then heating to r higher temperature in an inert environnent to consolidate the material.

3. Theprocess which coiisists in heating zhreads comprising a mixture of carbonazeous material and an oxid of tungsten in a reducing atmosphere under low pressure to reduce the oxid and eliminate carbon and then heating to a higher temperature in an inert environment to consolidate the tungstem 4. The process which consists in heating a plurality of threads comprising an oxid of tungsten-and a carbonaceous binder in hydrogen at low pressure and then heating at p a high temperature in a vacuum.

5. The process which consists in heating filamentary bodies comprising an oxid of" L S HANSEN. Witnesses A ALEX. F. MAonoNALo, BENJAMIN B. HULL. 

